1. Field of the Invention
The present invention relates to a production method of a dielectric lens, more specifically, it relates to a production method of a dielectric lens having a configuration wherein a matching layer is formed on the surface of a lens main body comprising a dielectric substance.
2. Description of the Related Art
Examples of dielectric lenses include a dielectric lens having a configuration wherein a matching layer 52 is formed on the surface of a lens main body 51 comprising a dielectric substance, with a lens mounting portion 53 formed integrally with the matching layer provided in the peripheral part as shown in FIGS. 10A and 10B.
In the production of such a dielectric lens, in general, the lens main body 51 and the matching layer 52 are formed by the injection molding method.
However, since the demand level for a dielectric lens is high in terms of the shape accuracy and the density homogeneity if the frequency band to be used is a millimeter wave band, it is difficult provide it with an ordinary injection molding method.
Therefore, for the production of a dielectric lens to be used in a millimeter wave band frequency, the following have been proposed:
(1) a method of conducting the homogeneous foaming molding by injecting a molding material with a foaming agent added thereto, and PA0 (2) a method of forming a lens main body by the cutting process of a block produced by attaching plates produced by the injection molding method, or a block produced by the extrusion molding method, producing a matching layer formed independently from the lens main body by the injection molding or the cutting process, and attaching the matching layer with the lens main body.
However, according to the above-mentioned (1) method of the homogeneous foaming molding, although the molding accuracy can be satisfied, a problem arises in that bubbles formed by foaming cast adverse effect in characteristics in the millimeter wave band.
Moreover, according to the above-mentioned method (2) method of the cutting process, since the cutting process requires time as well as the step of attaching the matching layer formed independently with the land main body requires labor, a problem is involved in the productivity decline and the production cost increase. Further, in some cases, at the time of attaching the lens main body and the matching layer, a dielectric substance needs to be charged in the gap therebetween, and thus a further labor may be necessary.